Stasis Predisposes Ileal Pouch Inflammation in a Rat Model of Ileal Pouch-Anal Anastomosis

Normal Ileal Mucus Is Inadequate for Epithelial Protection in Ileal Pouch Mucosa

BACKGROUND

Clinical, nonspecific pouchitis is common after restorative proctocolectomy for ulcerative colitis, but its cause is unknown. A possible lack of protection for the ileal mucosa in its role as a reservoir for colonic-type bacteria may be the missing piece in defining the causes of pouchitis.

OBJECTIVE

The study aimed to review the causes of pouchitis and introduce the hypothesis that inadequate mucus protection in the pouch, combined with a predisposition to abnormal inflammation, is the most common cause of nonspecific pouchitis.

DATA SOURCES

Review of PubMed and MEDLINE for articles discussing pouchitis and intestinal mucus.

STUDY SELECTION

Studies published from 1960 to 2023. The main search terms were "pouchitis," and "intestinal mucus," whereas Boolean operators were used with multiple other terms to refine the search. Duplicates and case reports were excluded.

MAIN OUTCOME MEASURES

Current theories about the cause of pouchitis, descriptions of the role of mucus in the physiology of intestinal protection, and evidence of the effects of lack of mucus on mucosal inflammation.

RESULTS

The crossreference of "intestinal mucus" with "pouchitis" produced 9 references, none of which discussed the role of mucus in the development of pouchitis. Crossing "intestinal mucus" with "pouch" resulted in 32 articles, combining "pouchitis" with "barrier function" yielded 37 articles, and "pouchitis" with "permeability" yielded only 8 articles. No article discussed the mucus coat as a barrier to bacterial invasion of the epithelium or mentioned inadequate mucus as a factor in pouchitis. However, an ileal pouch produces a colonic environment in the small bowel, and the ileum lacks the mucus protection needed for this sort of environment. This predisposes pouch mucosa to bacterial invasion and chronic microscopic inflammation that may promote clinical pouchitis in patients prone to an autoimmune response.

LIMITATIONS

No prior studies address inadequate mucus protection and the origin of proctitis. There is no objective way of measuring the autoimmune tendency in patients with ulcerative colitis.

CONCLUSIONS

Studies of intestinal mucus in the ileal pouch and its association with pouchitis are warranted.

Endoscopy in the Surgically Altered Bowel

Improved utilization of surgical interventions to improve patient outcomes has led to an increased need to endoscopically evaluate and treat the bowel after surgery. The best outcomes are attained when the endoscopist coordinates with the surgeon, and in some cases the pathologist or radiologist to plan the procedure. Understanding the anatomy and pathology anticipated can allow planning for sedation, bowel cleanse and equipment needed. Surgically altered anatomy can create challenges that with planning can be overcome. This article will review how to prepare and navigate several of the most commonly encountered surgical interventions.

Development of a total colectomy and ileorectal anastomosis rat model to evaluate colonic metaplasia

BACKGROUND

Ulcerative colitis is an idiopathic inflammatory condition of the colon that may require surgical intervention including proctocolectomy and either ileal pouch-anal anastomosis or in the pediatric population, low ileorectal anastomosis (IRA). Often, subsequent physiologic alteration (or colonic metaplasia) occurs in the anastomosed small bowel that includes changes in mucin content, villous blunting, and increased expression of WNT5A, a marker of colonic crypt regeneration. We developed a rat low IRA model to assess and study the development of colonic metaplasia.

MATERIALS AND METHODS

We subjected male Sprague-Dawley rats (n = 17) to total colectomy and low IRA surgery and evaluated healing periodically by endoscopic evaluation. The ileum upstream of the anastomosis was assessed by hematoxylin and eosin staining, and the mucin content was measured by high iron diamine-Alcian blue staining. Wnt5a transcripts were quantified by reverse transcription and quantitative polymerase chain reaction at the 8-wk study end point.

RESULTS

Although no gross endoscopic evidence of inflammation was seen throughout the course of the study, colonic metaplasia in the small bowel was detected in 7 out of 10 (70%) rats at the study end point. In rats with colonic metaplasia, enhanced expression of Wnt5a was evident at the study end point compared to levels in the terminal ileum at the time of surgery.

CONCLUSIONS

Within 4-8 wk, the majority of rats subjected to IRA developed colonic metaplasia defined by villous blunting, changes in mucin content, and increased expression of Wnt5a. This model provides a method to study small bowel colonic metaplasia.

Nonrelaxing Pelvic Floor Dysfunction Is an Underestimated Complication of Ileal Pouch-Anal Anastomosis

BACKGROUND & AIMS

Nonrelaxing pelvic floor dysfunction (N-RPFD), or dyssynergic defecation, is the paradoxical contraction and/or impaired relaxation of pelvic floor and anal muscles during defecation. Few studies have evaluated this disorder in patients with an ileal pouch-anal anastomosis (IPAA). We investigated the frequency of N-RPFD in patients with and without chronic pouchitis following IPAA and the effectiveness of biofeedback therapy within this population.

METHODS

We conducted a retrospective study of all patients with an IPAA who underwent anorectal manometry between January 2000 and March 2015 (n = 111). N-RPFD was diagnosed in patients with symptoms consistent with a pouch evacuation disorder and 1 or more of the following abnormal tests: anorectal manometry, balloon expulsion test, barium or magnetic resonance defecography, or external anal sphincter electromyography. Patients who completed biofeedback therapy were identified and assessed to determine symptomatic response.

RESULTS

Of the 111 patients evaluated, 83 (74.8%) met criteria for N-RPFD. A significantly higher proportion of patients with chronic pouchitis were diagnosed with N-RPFD than patients without chronic pouchitis (83.3% vs 62.2%, respectively; P = .012). Most patients diagnosed with N-RPFD had abnormal results from the balloon expulsion test (78.3%); 53.0% of patients diagnosed with N-RPFD had abnormal findings from external anal sphincter electromyography, 25.3% had abnormal defecography findings, and 20.5% had abnormal findings from anorectal manometry. Twenty-two patients completed biofeedback therapy: 15 patients (68.2%) had mild-moderate improvement and 5 patients (22.7%) had significant improvement of symptoms.

CONCLUSIONS

N-RPFD occurs in almost 75% of patients with an IPAA, especially in patients with chronic pouchitis. Biofeedback seems to be an effective therapy for patients with an IPAA and N-RPFD, but further studies are needed for validation.

Differences in short-term outcomes among patients undergoing IPAA with or without preoperative radiation: a National Surgical Quality Improvement Program analysis

BACKGROUND

Single-institution studies demonstrate a correlation between preoperative pelvic radiation and poor long-term pouch function after IPAA. The rarity of the radiated pelvis before these procedures limits the ability to draw conclusions on the effects of preoperative radiation on short-term outcomes, which may contribute to long-term pouch dysfunction.

OBJECTIVE

The purpose of this work was to better understand the impact of pelvic radiation on short-term outcomes in patients undergoing IPAA.

DESIGN

We conducted a retrospective review of the American College of Surgeons National Surgical Quality Improvement Program database (2005-2011).

SETTINGS

The study was conducted at all participating NSQIP institutions.

PATIENTS

The cohort was composed of patients undergoing nonemergent IPAA procedures.

MAIN OUTCOME MEASURES

Proportions of patients experiencing postoperative complications within 30 days were compared by Fisher exact and Wilcoxon rank-sum tests based on whether they received preoperative radiation. Multivariate logistic regression models controlled for the effects of multiple risk factors.

RESULTS

Included were 3172 patients receiving IPAA; 162 received pelvic radiation. The postoperative complication rate was not significantly different in patients receiving pelvic radiation versus not receiving pelvic radiation (p = 0.06). In a subset of patients with cancer diagnoses (n = 598), 157 received pelvic radiation; complication rates were not significantly different (p = 0.16). Patients receiving pelvic radiation had significantly lower rates of sepsis in both the overall and cancer diagnosis groups (p = 0.005 and p = 0.047), a finding which persisted after controlling for the effects of multiple risk factors (multivariate p values = 0.030 and 0.047).

LIMITATIONS

This was a retrospective database design with short-term follow-up.

CONCLUSIONS

Patients who received radiation before IPAA had no difference in overall 30-day complication rates but had significantly lower rates of sepsis when compared with patients not receiving pelvic radiation. The perceived inferior long-term pouch function in patients undergoing preoperative pelvic radiation does not appear to be attributable to increases in 30-day complications.

Surgical prophylaxis of pouchitis in ulcerative colitis

Ileal pouch-anal anastomosis (IPAA) is now the procedure of choice for most patients requiring proctocolectomy for ulcerative colitis. The J-shaped pouch, usually 15-20 cm in length, is easiest to construct and has functional outcomes identical to those of the more complex designs. IPAA is a complex procedure, and complications occur frequently. Despite the significant improvements this surgical advance has made on the quality of life in these patients, inflammation of the surgically created ileal pouch or pouchitis remains a major late postoperative complication that can often overshadow the benefits of this otherwise curative operation. Several inflammatory and noninflammatory complications can occur after IPAA. Pouchitis is the most common, occurring in ≈50% of patients. Whereas acute pouchitis can be treated rapidly and successfully in the majority of patients, refractory and chronic pouchitis remain therapeutic challenges to patients and physicians. The problem is believed to be caused by stasis of feces in the pouch with overgrowth of aerobic and anaerobic organisms. The size of the pouch has a significant influence on the incidence of pouchitis: a smaller pouch usually empties better than a larger pouch and so may be less susceptible to pouchitis.